1. Field of the Invention
The present invention relates to pivotal hand tools, such as pliers, cutters and the like and, in particular, to tools such as lineman's tools which are designed for use in applications where they may be exposed to high electrical voltage or current.
2. Description of the Prior Art
It is important in certain electrical applications that hand tools, such as pliers, cutters and the like, be electrically non-conductive to protect the user from electrical shock and to prevent short circuitry of electrical circuits. It is well known to provide electrically insulating sheaths or coatings on the handles of such tools, but such coatings provide limited electrical protection, being unsuitable for use in very high-voltage or high-current environments, such as may be encountered by an electrical utility lineman. Furthermore, such sheathing or coating can be degraded by cutting, scratching and the like, which seriously impairs its electrical insulating efficiency.
It is known to provide hand tools with handle portions formed entirely of electrically non-conductive or insulating materials, such as plastics and the like. Such tools have worked effectively in protecting the user from shock resulting from electrical conductivity through the handle. However, it has been typically necessary that the working portions, such as the jaws of pliers, cutters and the like, be formed of metal in order to provide the requisite strength, hardness and toughness for the particular tool application. Such metal working parts are subject to sparking and/or to magnetization, which renders them unsuitable for certain applications.
Another difficulty with cutter tools is that the cutting edges tend to wear and dull with use, necessitating reconditioning. It s known to provide hand tools such as pliers, cutters and the like, with replaceable metal jaw inserts, but this does not avoid the sparking and magnetization problem.
Various types of cutting tools have been provided heretofore with blades formed of material, such as ceramic, which has excellent wear-resistance characteristics. However, most ceramic materials are less tenacious than metals and have a tendency to chip or crack and, because of their hardness, once chipped, they are difficult to recondition. Furthermore, previous attempts at ceramic cutter design have proved to be difficult and expensive, since cutting edge and platen designs cannot be molded directly and require expensive machining.